Medical treatment often requires the administration of a therapeutic agent (e.g., medicament, drugs, etc.) to a particular part of a patient's body. Some maladies, however, are difficult to treat with currently available therapies and/or require administration of drugs to anatomical regions to which access is difficult to achieve.
A patient's eye is a prime example of a difficult-to-reach anatomical region, and many vision-threatening diseases, including retinitis pigmentosa, age-related macular degeneration (AMD), diabetic retinopathy, and glaucoma, are difficult to treat with many of the currently available therapies. For example, oral medications can have systemic side effects; topical applications may sting and engender poor patient compliance; injections generally require a medical visit, can be painful, and risk infection; and sustained-release implants must typically be removed after their supply is exhausted.
Another example is cancer, such as breast cancer or meningiomas, where large doses of highly toxic chemotherapies, such as rapamycin, bevacizumab (e.g., Avastin®), or irinotecan (CPT-11), are typically administered to the patient intravenously, which may result in numerous undesired side effects outside the targeted area.
Implantable drug-delivery devices, which may have a refillable drug reservoir, cannula, and check valve, etc., generally allow for controlled delivery of pharmaceutical solutions to a specified target. As drug within the drug reservoir depletes, the physician can refill the reservoir with, for example, a syringe, while leaving the device implanted within the patient's body.
If, however, the syringe needle is inadvertently inserted too far into the device during the refilling, the device can be damaged. Such damage may necessitate removal of the device and its replacement with another, thereby obviating some of the advantage of using the device. Even if the device is not damaged, insertion of the needle too far into the device can, for example, embed the needle tip in the bottom wall of the device's reservoir, thereby clogging the needle's lumen. Additionally, the improper insertion of the needle into the device may lead to the delivery of the drug into an improper location.
A need exists, therefore, for improved implantable drug-delivery devices, and apparatus and methods for refilling such devices.